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IHSM4825RE271L

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P22
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM Controllers
10 ______________________________________________________________________________________
Pin Descriptions (continued)
PIN
MAX5071A/
MAX5071B
MAX5071C
NAME FUNCTION
1 1 COMP
COMP is level-shifted and connected to the inverting input of the PWM comparator. Pull
up COMP to VREF through a resistor and connect an optocoupler from COMP to GND for
proper operation.
2 — SYNC
Bidirectional Synchronization Input. When synchronizing with other
MAX5071A/MAX5071Bs, the higher frequency part synchronizes all other devices.
—2
ADV_CLK
ADV_CLK is an 85ns clock output pulse preceding the rising edge of OUT (see Figure 4).
Use the pulse to drive the secondary-side synchronous rectifiers through a pulse
transformer or an optocoupler (see Figure 8).
33CS
Input to the PWM Comparator and Overcurrent Protection Comparator. The current-
sense signal is compared to the voltage at COMP.
44R
T
/C
T
Timing Resistor and Capacitor Connection. A resistor R
T
from R
T
/C
T
to VREF and
capacitor C
T
from R
T
/C
T
to GND set the oscillator frequency.
5 5 GND
Power-Supply Ground. Place the V
CC
and VREF bypass capacitors close to the IC to
minimize ground loops.
6 6 OUT MOSFET Driver Output. OUT connects to the gate of the external n-channel MOSFET.
77V
CC
Power-Supply Input for MAX5071. Bypass V
CC
to GND with a 0.1µF ceramic capacitor or
a parallel combination of a 0.1µF and a higher value ceramic capacitor.
88V
REF
5V Reference Output. Bypass VREF to GND with a 0.1µF ceramic capacitor or a parallel
combination of a 0.1µF and a higher value ceramic capacitor.
MAX5071A/MAX5071B/MAX5071C
Detailed Description
The MAX5070/MAX5071 current-mode PWM controllers
are designed for use as the control and regulation core of
flyback or forward topology switching power supplies.
These devices incorporate an integrated low-side driver,
adjustable oscillator, error amplifier (MAX5070A/
MAX5070B only), current-sense amplifier, 5V reference,
and external synchronization capability (MAX5071A/
MAX5071B only). An internal +26.5V current-limited V
CC
clamp prevents overvoltage during startup.
Five different versions of the MAX5070/MAX5071 are
available. The MAX5070A/MAX5070B are the standard
versions with a feedback input (FB) and internal error
amplifier. The MAX5071A/MAX5071B include bidirection-
al synchronization (SYNC). This enables multiple
MAX5071A/MAX5071Bs to be connected and synchro-
nized to the device with the highest frequency. The
MAX5071C includes an ADV_CLK output, which pre-
cedes the MAX5071C’s drive output (OUT) by 110ns.
Figures 1, 2, and 3 show the internal functional diagrams
of the MAX5070A/MAX5070B, MAX5071A/MAX5071B,
and MAX5071C, respectively. The MAX5070A/
MAX5071A are capable of 100% maximum duty cycle.
The MAX5070B/MAX5071B/MAX5071C are designed to
limit the maximum duty cycle to 50%.
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM Controllers
______________________________________________________________________________________ 11
UVLO
REFERENCE
2.5V
PREREGULATOR
5V
VOLTAGE-
DIVIDER
THERMAL
SHUTDOWN
EN-REF
BG
SNS
V
DD
5V REGULATOR
VOLTAGE-
DIVIDER
8
7
26.5V
V
CC
VREF
2.5V
VP
REG_OK
DELAY
S
R
Q
OSC Q
4
R
T
/C
T
6
OUT
ILIM
CPWM
1V
EN-DRV-BAR
R
2R
VEA
3
5
2
1
CS
GND
FB
COMP
CLK
MAX5070A/MAX5070B
VP
2.5V
16V/10V
100% MAX DUTY CYCLE (MAX5070A)
50% MAX DUTY CYCLE (MAX5070B)
Figure 1. MAX5070A/MAX5070B Functional Diagram
MAX5070/MAX5071
Current-Mode Control Loop
The advantages of current-mode control over voltage-
mode control are twofold. First, there is the feed-forward
characteristic brought on by the controller’s ability to
adjust for variations in the input voltage on a cycle-by-
cycle basis. Secondly, the stability requirements of the
current-mode controller are reduced to that of a single-
pole system unlike the double pole in the voltage-mode
control scheme.
The MAX5070/MAX5071 use a current-mode control loop
where the output of the error amplifier is compared to the
current-sense voltage (V
CS
). When the current-sense sig-
nal is lower than the noninverting input of the PWM com-
parator, the output of the CPWM comparator is low and
the switch is turned on at each clock pulse. When the
current-sense signal is higher than the inverting input of
the CPWM, the output of the CPWM comparator is high
and the switch is turned off.
High-Performance, Single-Ended, Current-Mode
PWM Controllers
12 ______________________________________________________________________________________
UVLO
REFERENCE
2.5V
PREREGULATOR
5V
VOLTAGE-
DIVIDER
THERMAL
SHUTDOWN
EN-REF
BG
SNS
V
DD
5V REGULATOR
VOLTAGE-
DIVIDER
8
7
26.5V
V
CC
VREF
2.5V
VP
REG_OK
DELAY
S
R
Q
OSC Q
4
R
T
/C
T
6
OUT
ILIM
CPWM
1V
EN-DRV-BAR
R
2R
3
5
1
2
CS
GND
COMP
SYNC
CLK
MAX5071A/MAX5071B
VP
2.5V
1V
BIDIRECTIONAL
SYNC
100% MAX DUTY CYCLE (MAX5071A)
50% MAX DUTY CYCLE (MAX5071B)
16V/10V
Figure 2. MAX5071A/MAX5071B Functional Diagram
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P22

IHSM4825RE271L

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Buy IHSM4825RE271L
Manufacturer:
Vishay / Dale
Description:
Fixed Inductors IHSM-4825 270 15% RC2
Lifecycle:
New from this manufacturer.
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